Method and system for spinal cord stimulation prior to and during a medical procedure

ABSTRACT

A method of performing a medical procedure, such as surgery, is provided. The spinal cord is stimulated in order to control at least one physiological function. The medical procedure is performed and stimulation of the spinal cord is stopped.

FIELD OF THE INVENTION

This invention relates to methods for performing a medical procedure,especially a procedure during which it is desirable to providestimulation to the spinal column. More particularly, this inventionrelates to methods and systems of stimulating the spinal cord during amedical procedure in which the beating of a heart is modified to allowthe procedure to be performed or to allow blood flow to be controlled.

BACKGROUND OF THE INVENTION

Stimulation of the spinal cord can result in control of motor responses,nerve responses and other organ functions. For example, stimulation ofthe spinal cord in one area may control the function of the bladder.Stimulation of the spinal cord at yet another area may control thepatient's ability to feel pain.

In a typical medical procedure, it may be desirable to stimulate thespinal cord in order to control the function of an organ. In particular,medical procedures in which the flow of blood is controlled, usually bystopping the heart, may benefit from using stimulation of the spinalcord to reduce pain.

Currently, stimulation of the spinal cord is used to control thefunctions of organs, the responses of organs and the responses of nervesin the context of post surgical treatment. That is, a spinal cordstimulator may be inserted in the spine to control pain after a surgicalprocedure has been done.

It would be desirable therefore to stimulate the spinal cord during amedical procedure to control the function of one or more organs.

It would further be desirable to stimulate the spinal cord to ease painduring a medical procedure.

SUMMARY OF THE INVENTION

One aspect of the present invention provides a method of performing amedical procedure. A spinal cord is stimulated to control at least onephysiological function. The medical procedure is performed. Stimulationof the spinal cord is then stopped. The physiological function may be afunction of the lungs or the heart. The physiological function may alsobe the reduction of pain.

Stimulation of the cord may be intermittent. Drugs, such as abeta-blocker, a cholinergic agent, a cholinesterase inhibitor, a calciumchannel blocker, a sodium channel blocker, a potassium channel agent,adenosine, an adenosine receptor agonist, an adenosine deaminaseinhibitor, dipyridamole, a monoamine oxidase inhibitor, digoxin,digitalis, lignocaine, a bradykinin agent, a serotoninergic agonist, anantiarrythmic agent, a cardiac glycoside, a local anesthetic, atropine,a calcium solution, an agent that promotes heart rate, an agent thatpromotes heart contractions, dopamine, a catecholamine, an inotropeglucagon, a hormone, forskolin, epinephrine, norepinephrine, thyroidhormone, a phosphodiesterase inhibitor, prostacyclin, prostaglandin anda methylxanthine, may be delivered during the procedure. These drugs maybe naturally occurring or chemically synthesized.

The medical procedure may be one of the following: surgical procedures,non-surgical procedures, endoscopic procedures, fluoroscopic procedures,stent delivery procedures, aortic aneurysm repairs, cranial aneurysmrepairs, delivery of drugs, delivery of biological agents, cardiacsurgery with cardiopulmonary bypass circuits, cardiac surgery withoutcardiopulmonary bypass circuits, brain surgery, cardiograms, heart valverepair, heart valve replacement, MAZE procedures, revascularizationprocedures, transmyocardial revascularization, percutaneous myocardialrevascularization, CABG procedures, anastomosis procedures, beatingheart surgery, vascular surgery, neurosurgery, brain surgery,electrophysiology procedures, diagnostic procedures, therapeuticprocedures, ablation procedures, ablation of arrhythmias, endovascularprocedures, treatment of the liver, treatment of the spleen, treatmentof the heart, treatment of the lungs, treatment of major blood vessels;non-invasive procedures, invasive procedures, port-access procedures,imaging procedures, CAT scan procedures, MRI procedures, gene therapyprocedures, cellular therapy procedures, cancer therapy procedures,radiation therapy procedures, transplantation procedures, coronaryangioplasty procedures, atherectomy procedures, atherosclerotic plaqueremoval procedures and birthing procedures. The spinal cord may beaccessed via intrathecal access, epidural access, and transcutaneousaccess.

Another aspect of the present invention provides a system for performinga medical procedure. The system includes a spinal stimulator to reducepain during the medical procedure, a nerve stimulator in communicationwith the spinal stimulator to inhibit beating of the heart; and acardiac stimulator in communication with the spinal stimulator tostimulate beating of the heart. The system may also include drugdelivery means for delivering at least one drug during the medicalprocedure such as a spray, a cream, an ointment, a medicament, a pill, apatch, a catheter, a cannula, a needle and syringe, a pump, and aniontophoretic drug delivery device. The nerve stimulator may stimulatevagus nerve fibers, hypoglossal nerve fibers, phrenic nerve fibers,parasympathetic nerve fibers, and sympathetic nerve fibers, a vagalnerve, a carotid sinus nerve, a fat pad. The spinal stimulator comprisesone or more electrodes such as spinal stimulation electrodes,balloon-type electrodes, basket-type electrodes, umbrella-typeelectrodes, suction-type electrodes, guided catheters, guidedelectrodes, steerable catheters, and steerable electrodes. The nervestimulator also comprises one or more electrodes such as nervestimulation electrodes, endotracheal electrodes, endoesophagealelectrodes, intravascular electrodes, transcutaneous electrodes,intracutaneous electrodes, balloon-type electrodes, basket-typeelectrodes, umbrella-type electrodes, tape-type electrodes, suction-typeelectrodes, screw-type electrodes, barb-type electrodes, bipolarelectrodes, monopolar electrodes, metal electrodes, wire electrodes,patch electrodes, cuff electrodes, clip electrodes, needle electrodesand probe electrodes. The cardiac stimulator also comprises one or moreelectrodes such as cardiac stimulation electrodes, clip electrodes,needle electrodes, probe electrodes, pacing electrodes, epicardialelectrodes, patch electrodes, intravascular electrodes, balloon-typeelectrodes, basket-type electrodes, tape-type electrodes, umbrella-typeelectrodes, suction-type electrodes, endotracheal electrodes,endoesophageal electrodes, transcutaneous electrodes, intracutaneouselectrodes, screw-type electrodes, barb-type electrodes, bipolarelectrodes, monopolar electrodes, metal electrodes, wire electrodes andcuff electrodes.

Another aspect of the present invention provides a method of performingheart surgery. A spinal cord is stimulated to control pain. A nerve isstimulated to reduce the beating of a heart. The heart is operated upon.Stimulation of the nerve is reduced or stopped. The heart is stimulatedto cause it to beat. The nerve is restimulated to re-inhibit beating ofthe heart and the surgery is continued.

Another aspect of the present invention provides a device forcontrolling pain during a medical procedure. The device includes aprocessor connected to a spinal stimulation electrode and a nervestimulation electrode. The processor processes output from the spinalstimulation electrode and adjusts output from the nerve stimulationelectrode based on output from the spinal stimulation electrode. Thedevice may also include a cardiac stimulation electrode operativelyconnected to the processor, wherein the processor processes output fromthe spinal stimulation electrode and adjusts output from the cardiacstimulation electrode based on output from the spinal stimulationelectrode.

Another aspect of the present invention provides a method of deliveringa baby. The spinal cord is stimulated to control pain. The baby isdelivered. Then stimulation of the spinal cord is stopped.

The foregoing, and other, features and advantages of the invention willbecome further apparent from the following detailed description of thepresently preferred embodiments, read in conjunction with theaccompanying drawings. The detailed description and drawings are merelyillustrative of the invention rather than limiting, the scope of theinvention being defined by the appended claims in equivalence thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of one embodiment of a system for stimulatingthe spinal cord during a medical procedure in accordance with thepresent invention;

FIG. 2 is a schematic view of one embodiment of a medical device inaccordance with the present invention;

FIG. 3 is a flow diagram of one embodiment of a method of performing amedical procedure in accordance with the present invention; and

FIG. 4 is a timeline view of one embodiment of a system for stimulatingthe spinal cord during a medical procedure in accordance with thepresent invention.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

FIG. 1 shows a schematic view of one embodiment of a system forperforming a medical procedure in accordance with the present inventionat 100. System 100 comprises a spinal cord stimulator 3, a nervestimulator 10, and a cardiac stimulator 20. System 100 may also featurea controller 30 and a breathing regulator 40.

Spinal cord stimulator 3 may be an implantable pulse generator. Spinalcord stimulator 3 may also be any suitable stimulator that provides anelectrical impulse to the spine. For example, spinal cord stimulator 3may be a single lead or a suitable arrangement of electrical leads.Electrodes that may be used in spinal cord stimulator 3 may be, forexample, cuff-type, needle-type, probe-type, transcutaneous,intracutaneous, patch-type, balloon-type, basket-type, umbrella-type,tape-type, screw-type, barb-type, metal, wire or suction-typeelectrodes. Guided or steerable catheter devices comprising electrodesmay be used alone or in combination with the spinal cord stimulationelectrodes. For example, a catheter comprising one or more wire, metalstrips or metal foil electrodes or electrode arrays may be used.Application of an electrical stimulus to the spinal cord may include,but is not limited to bipolar and/or monopolar techniques.

All or a portion of spinal cord stimulator may be placed in any suitablemanner for providing stimulation to the spine. Spinal cord stimulator 3may be placed invasively or non-invasively. In one embodiment, all or aportion of spinal cord stimulator 3 is implanted adjacent the spine.Alternatively, all or a portion of spinal cord stimulator 3 may beimplanted adjacent specific vertebrae. Electrical stimulation may becarried out on more than one area of the spinal cord simultaneously orsequentially. Alternatively, spinal cord stimulator 3 may be a guided orsteerable electrode, which allows its position to be adjusted during themedical procedure. Different electrode positions are accessible throughvarious access openings along the spinal cord. Spinal cord stimulator 3may be positioned endoscopically through a percutaneous port, through anincision in the spine, placed on the skin or in combinations thereof.The present invention may include various electrodes, catheters andelectrode catheters suitable for spinal cord stimulation. Other suitableplacements of spinal cord stimulator 3 may be possible.

Spinal cord stimulator 3 may be powered by AC current, DC current or itmay be battery powered either by a disposable or re-chargeable battery.Spinal cord stimulator 3 may be configured to synchronize activation anddeactivation of breathing regulator 40 with vagal stimulation, therebyminimizing or eliminating unwanted heart or chest motion associated withthe patient's breathing. Alternatively, spinal cord stimulator 3 may beplaced so as to control the patient's lungs to minimize or eliminateunwanted heart motion. Spinal cord stimulator 3 may comprise a surgeoncontrolled switch box. A visual and/or audible signal used to alert asurgeon to the completion or resumption of spinal cord stimulation maybe incorporated into spinal cord stimulator 3. For example, a beepingtone or flashing light that increases in frequency as the spinalstimulation period ends or begins may be used. A switch may also beincorporated in or on one of the surgeon's instruments, such as surgicalsite retractor, or any other location easily and quickly accessed by thesurgeon for regulation of the spinal cord stimulator 3 by the surgeon.The switch may be, for example, a hand switch, a foot switch, or avoice-activated switch comprising voice-recognition technologies.

A visual and/or audible signal used to alert a surgeon to the completionor resumption of spinal cord stimulation may be incorporated into spinalcord stimulator 3. For example, a beeping tone or flashing light thatincreases in frequency as the spinal stimulation period should end orbegin may be used.

Spinal cord stimulator 3 may be slaved to nerve stimulator 10 or cardiacstimulator 20. Software controlling spinal cord stimulator 3 may bedesigned to automatically stimulate the spine if nerve stimulator 10 orcardiac stimulator 20 is on.

System 100 may also include a nerve stimulator 10. In one embodiment,the nerve stimulator 10 may be used to electrically manipulate cardiacrhythm by stimulating the vagus nerve. This vagal stimulation mayproduce asystole (slowing or stopping of the heart's beating.) Once thisinduced asystole is stopped, i.e. once the vagal stimulation is stopped,the heart may be allowed to return to its usual cardiac rhythm.Alternatively, the heart may be paced with an electrical pacing system,thereby maintaining a normal cardiac output. Vagal stimulation, alone orin combination with electrical pacing, may be used selectively andintermittently to allow a surgeon to perform a medical procedure duringintermittent periods of asystole.

It is known that stimulation of the vagus nerve can reduce the sinusrate, as well as prolong AV conduction time or, if stimulation energiesare high enough, induce AV node block. Use of vagal nerve stimulation totreat supraventricular arrhythmias and angina pectoris is disclosed inthe article “Vagal Tuning” by Bilgutay et al., Journal of Thoracic andCardiovascular Surgery, Vol. 56, No. 1, July, 1968, pp. 71-82. It isalso known that stimulation of the carotid sinus nerve produces asimilar result, as disclosed in the article “Carotid Sinus NerveStimulation in the Treatment of Angina Pectoris and SupraventricularTachycardia” by Braunwald et al., published in California Medicine, Vol.112, pp. 41-50, March, 1970.

As set forth in “Functional Anatomy of the Cardiac Efferent Innervation”by Randall et al., in Neurocardiology, edited by Kulbertus et al, FuturaPublishing Co., 1988, direct surgical excision of the fat pad associatedwith the SA node affects the functioning of the SA node withoutsignificantly affecting the AV node. Similarly, excision of the fat padassociated with the AV node affects functioning of the AV node withoutsignificantly affecting the SA node.

As set forth in the article “Parasympathetic Postganglionic Pathways tothe Sinoatrial Node,” Bluemel et al., Am. J. Physiol. 259, (Heart Circ.Physiol. 28) H1504-H1510, 1990, stimulation of the fat pad associatedwith the SA node results in slowing of the sinus rate without theaccompanying prolongation of AV conduction time which normally resultsfrom vagal nerve stimulation. The article also indicates thatstimulation of the fat pad associated with the AV node is believed toproduce corresponding effects limited to the AV node, i.e., extension ofthe AV conduction time without concurrent slowing of the sinus rate.

As set forth in the article “Neural Effects on Sinus Rate and AtrialVentricular Conduction Produced by Electrical Stimulation From aTransvenous Electrode Catheter in the Canine Right Pulmonary Artery” byCooper et al., published in Circulation Research, Vol. 46, No. 1,January, 1980, pp. 48-57, the fat pads associated with both the AV nodeand the SA node may be stimulated by means of electrodes located in theright pulmonary artery. The results obtained include both a depressionof the sinus rate and a prolongation of the AV conduction time inresponse to continuous stimulation at 2-80 Hz at up to 50 ma.

Generally in healthy individuals, the SA node functions as thepacemaker. Normal heart rhythm associated with the SA node is typicallyreferred to as sinus rhythm. When the SA node fails, the AV nodegenerally takes over creating a heart rate of approximately 35 to 60beats per minute. Heart rhythm associated with the AV node is typicallyreferred to as nodal rhythm. When the AV node itself is blocked orinjured, a new even slower pacemaker site may form at the junction ofthe AV node and the His bundle. Heart rhythm associated with thisjunction is typically referred to as junctional escape rhythm. When thisjunction site is inhibited, the Purkinje fibers in the His bundle orbelow may act as a pacemaker creating a heart rate of approximately 30beats per minute. Heart rhythm associated with the Purkinje fibers istypically referred to as idioventricular rhythm.

In one embodiment of the present invention, nerve stimulator 10 may beused to electrically manipulate cardiac rhythm by stimulating thecarotid sinus nerve, the fat pad associated with the SA node, the fatpad associated with the AV node, the junction of the AV node and the Hisbundle and/or the Purkinje fibers.

In one embodiment of the present invention, nerve stimulator 10 is usedalone or in combination with other heart rate inhibiting agents totemporarily stop or slow the beating heart, thereby eliminating orreducing heart motion and/or blood flow during a medical procedure. Forexample, the present invention may be used to eliminate or reduce motionin the anastomosis field during CABG procedures such that a facilitatedanastomosis procedure may be performed safely and effectively. Thenumber of occasions that the vagal nerve may be stimulated depends onthe type of medical procedure to be performed. Likewise, the type ofmedical procedure to be performed will dictate the duration of theindividual electrical stimulations.

Nerve stimulator 10 may be powered by AC current, DC current or it maybe battery powered either by a disposable or re-chargeable battery.Nerve stimulator 10 may be configured to synchronize activation anddeactivation of breathing regulator 40 with vagal stimulation, therebyminimizing or eliminating unwanted heart and chest motion associatedwith the patient's breathing. Nerve stimulator 10 may comprise a surgeoncontrolled switch box. A switch may be incorporated in or on one of thesurgeon's instruments, such as surgical site retractor, or any otherlocation easily and quickly accessed by the surgeon for regulation ofthe nerve stimulator 10 by the surgeon. The switch may be, for example,a hand switch, a foot switch, or a voice-activated switch comprisingvoice-recognition technologies.

A visual and/or audible signal used to alert a surgeon to the completionor: resumption of vagal nerve stimulation may be incorporated into nervestimulator 10. For example, a beeping tone or flashing light thatincreases in frequency as the nerve stimulation period should end orbegin may be used.

Nerve stimulator 10 may be slaved to cardiac stimulator 20 or cardiacstimulator 20 may be slaved to nerve stimulator 10. For example, theoutput of cardiac stimulator 20 may be off whenever the output of nervestimulator 10 is on. Software controlling cardiac stimulator 20 may bedesigned to automatically commence cardiac pacing if the heart does notresume beating within a pre-determined interval after cessation of vagalnerve stimulation. In addition, the software controlling nervestimulator 10 may be designed to automatically stop vagal nervestimulation if the heart has been stopped for too long.

System 100 may also include cardiac stimulator 20 which may be used tostimulate the heart as desired. As with nerve stimulator 10, cardiacstimulator 20 may be intermittently stopped and started to allow thesurgeon to perform individual steps of a medical procedure.

Cardiac stimulator 20 may be a conventional ventricular demand pacer ordual chamber (atrial-ventricular) pacer. Cardiac stimulator 20 may bepowered by AC current, DC current or it may be battery powered either bya disposable or re-chargeable battery. Cardiac stimulator 20 may beconfigured to synchronize activation and deactivation of breathingregulator 40 with pacing, thereby minimizing or eliminating unwantedheart and chest motion associated with the patient's breathing. Cardiacstimulator 20 may be any conventional pacing device suitable forventricular demand pacing and having leads electrically coupled to aswitch box. Cardiac stimulator 20 may be combined in a single unit witha switch box. Cardiac stimulator 20 may comprise a surgeon controlledswitch box. A switch may be incorporated in or on one of the surgeon'sinstruments, such as surgical site retractor, or any other locationeasily and quickly accessed by the surgeon for regulation of the cardiacstimulator by the surgeon. The switch may be, for example, a handswitch, a foot switch, or a voice-activated switch comprisingvoice-recognition technologies. A single switch may be used to regulateboth cardiac stimulator 20 and nerve stimulator 10.

A visual and/or audible signal used to prepare a surgeon for theresumption of pacing may be incorporated into cardiac stimulator 20. Forexample, a beeping tone or flashing light that increases in frequency asthe pacing period ends may be used. A single signaling method or devicemay be used for both cardiac stimulator 20 and nerve stimulator 10.

Spinal cord stimulator 3, nerve stimulator 10 and/or cardiac stimulator20 may be slaved to a robotic system or a robotic system may be slavedto spinal cord stimulator 3, nerve stimulator 10 and/or cardiacstimulator 20. Breathing regulator 40 and other components may also beslaved to such a system. Computer and voice-controlled robotic systemsthat position and maneuver endoscopes and/or other surgical instrumentsfor performing microsurgical procedures such as anastomoses throughsmall incisions may be used by a surgeon to perform precise and delicatemaneuvers. These robotic systems may allow a surgeon to perform avariety of microsurgical procedures including endoscopic CABG.Endoscopic CABG may allow multiple occluded coronary arteries to bebypassed without a thoracotomy or mini-thoracotomy. Heart valve repairand replacement may also be other surgical applications for theserobotic systems. In general, robotic systems may include head-mounteddisplays which integrate 3-D visualization of surgical anatomy andrelated diagnostic and monitoring data, miniature high resolution 2-Dand 3-D digital cameras, a computer, a high power light source and astandard video monitor.

System 100 may also include a breathing regulator 40. In one embodiment,the breathing regulator 40 may be used to stimulate the phrenic nerve inorder to provide a diaphragmatic pacemaker. Breathing regulator 40 maycomprise one or more electrodes for supplying electrical current to thephrenic nerve to control breathing during vagal and/or cardiacstimulation and/or destimulation. Electrodes used to stimulate thephrenic nerve may be, for example, non-invasive, e.g., clips, orinvasive, e.g., needles or probes. The application of an electricalstimulus to the phrenic nerve may include, but is not limited to bipolarand/or monopolar techniques. Different electrode positions areaccessible through various access openings, for example, in the cervicalor thorax regions. Nerve stimulation electrodes may be positionedthrough a thoracotomy, sternotomy, endoscopically through a percutaneousport, through a stab wound or puncture, through a small incision, placedon the skin or in combinations thereof. The present invention mayinclude various electrodes, catheters and electrode catheters suitablefor phrenic nerve stimulation to control breathing.

Phrenic nerve stimulation electrodes may be intravascular, patch-type,balloon-type, basket-type, umbrella-type, tape-type, cuff-type,suction-type, screw-type, barb-type, bipolar, monopolar, metal, wire,endotracheal, endoesophageal, intravascular, transcutaneous orintracutaneous electrodes. Guided or steerable catheter devicescomprising electrodes may be used alone or in combination with the nervestimulation electrodes. For example, a catheter comprising one or morewire, metal strips or metal foil electrodes or electrode arrays may beused. The catheter may comprise, for example, a balloon that may beinflated with air or liquid to press the electrodes firmly against avessel wall that lays adjacent the phrenic nerve.

Phrenic nerve stimulation electrodes may be oriented in any fashionalong the catheter device, including longitudinally or transversely.Various techniques such as ultrasound, fluoroscopy and echocardiographymay be used to facilitate positioning of the electrodes. If desired ornecessary, avoidance of obstruction of blood flow may be achieved withnotched catheter designs or with catheters which incorporate one or moretunnels or passageways.

In another embodiment, the breathing regulator 40 may comprise aconnector which interfaces with a patient's respirator, and sends alogic signal to activate or deactivate the respirator to controlbreathing during vagal and/or cardiac stimulation and/or destimulation.

FIG. 2 shows one embodiment of the present invention at 200. In thisembodiment, the elements named above may be combined or connected to acontrol unit along with other components. The unit 200 may be used tocoordinate the various elements. Unit 200 may incorporate a controlleror any suitable processor 230.

Spinal cord stimulator 203 may be incorporated into unit 200. Forexample, FIG. 2 shows an electrode for spinal stimulation at 203.

Spinal stimulation electrodes 203 may be any suitable electrodesincluding: intravascular, transcutaneous, intracutaneous, patch-type,cuff-type, tape-type, screw-type, barb-type, metal, wire, balloon-type,basket-type, umbrella-type or suction-type electrodes. Guided orsteerable catheter devices comprising electrodes may be used alone or incombination with the spinal cord stimulation electrodes 203. Forexample, a catheter comprising one or more wire, metal strips or metalfoil electrodes or electrode arrays may be inserted adjacent the spine.Spinal stimulation electrodes 203 may be oriented in any fashion alongthe catheter device, including longitudinally or transversely. Varioustechniques such as ultrasound, fluoroscopy and echocardiography may beused to facilitate positioning of the electrodes.

In one embodiment of the present invention, the location of theelectrodes 203 is chosen to elicit maximum stimulation to the spinalcord while preventing current spread to adjacent tissues. Furthermore, anon-conductive material such as plastic may be employed to sufficientlyenclose the electrodes of all the configurations to shield them from thesurrounding tissues and vessels, while exposing their confronting edgesand surfaces for positive contact with the spinal cord.

Spinal electrode 203 may be in communication with a processor as shownin FIG. 2. The processor may thus be used to process the pulses beingtransmitted from spinal stimulator 203. The processor may storeinformation about the pulses being generated. The processor may also beused to control or monitor the level or duration of spinal stimulationthat occurs.

Unit 200 may also incorporate a nerve stimulator. For example, FIG. 2shows an electrode for nerve stimulation at 210. Electrodes used tostimulate a nerve such as the vagal nerve may be, for example,non-invasive, e.g., clips, or invasive, e.g., needles or probes. Theapplication of an electrical stimulus to the right or left vagal nervemay include, but is not limited to bipolar and/or monopolar techniques.Different electrode positions are accessible through various accessopenings, for example, in the cervical or thorax regions. Nervestimulation electrodes 210 may be positioned through a thoracotomy,sternotomy, endoscopically through a percutaneous port, through a stabwound or puncture, through a small incision in the neck or chest,through the internal jugular vein, the esophagus, the trachea, placed onthe skin or in combinations thereof. Electrical stimulation may becarried out on the right vagal nerve, the left vagal nerve or to bothnerves simultaneously or sequentially. The present invention may includevarious electrodes, catheters and electrode catheters suitable for vagalnerve stimulation to temporarily stop or slow the beating heart alone orin combination with other heart rate inhibiting agents.

Nerve stimulation electrodes 210 may be endotracheal, endoesophageal,intravascular, transcutaneous, intracutaneous, patch-type, balloon-type,cuff-type, basket-type, umbrella-type, tape-type, screw-type, barb-type,metal, wire or suction-type electrodes. Guided or steerable catheterdevices comprising electrodes may be used alone or in combination withthe nerve stimulation electrodes 210. For example, a catheter comprisingone or more wire, metal strips or metal foil electrodes or electrodearrays may be inserted into the internal jugular vein to make electricalcontact with the wall of the internal jugular vein, and thus stimulatethe vagal nerve adjacent to the internal jugular vein. Access to theinternal jugular vein may be via, for example, the right atrium, theright atrial appendage, the inferior vena cava or the superior venacava. The catheter may comprise, for example, a balloon that may beinflated with air or liquid to press the electrodes firmly against thevessel wall. Similar techniques may be performed by insertion of acatheter-type device into the trachea or esophagus. Additionally,tracheal tubes and esophageal tubes comprising electrodes may be used.

Nerve stimulation electrodes 210 may be oriented in any fashion alongthe catheter device, including longitudinally or transversely. Varioustechniques such as ultrasound, fluoroscopy and echocardiography may beused to facilitate positioning of the electrodes. If desired ornecessary, avoidance of obstruction of blood flow may be achieved withnotched catheter designs or with catheters which incorporate one or moretunnels or passageways.

In one embodiment of the present invention, the location of theelectrodes 210 is chosen to elicit maximum bradycardia effectivenesswhile minimizing current spread to adjacent tissues and vessels and toprevent the induction of post stimulation tachycardia. Furthermore, anon-conductive material such as plastic may be employed to sufficientlyenclose the electrodes of all the configurations to shield them from thesurrounding tissues and vessels, while exposing their confronting edgesand surfaces for positive contact with the vagal nerve or selectedtissues.

Unit 200 may also incorporate a cardiac stimulator. For example, FIG. 2shows an electrode for stimulation of the heart at 220. Cardiacelectrodes 220 used to stimulate the heart may be, for example,non-invasive, e.g., clips, or invasive, e.g., needles or probes.Electrodes 220 may be positioned through a thoracotomy, sternotomy,endoscopically through a percutaneous port, through a stab wound orpuncture, through a small incision in the chest, placed on the chest orin combinations thereof. The present invention may also use variouselectrodes, catheters and electrode catheters suitable for pacing theheart, e.g., epicardial, patch-type, intravascular, balloon-type,basket-type, umbrella-type, tape-type electrodes, suction-type, pacingelectrodes, endotracheal electrodes, endoesophageal electrodes,transcutaneous electrodes, intracutaneous electrodes, screw-typeelectrodes, barb-type electrodes, bipolar electrodes, monopolarelectrodes, metal electrodes, wire electrodes and cuff electrodes.Guided or steerable catheter devices comprising electrodes may be usedalone or in combination with the electrodes.

Controller 230 may be used to gather information from spinal stimulationelectrodes 203, nerve stimulation electrodes 210 and cardiac stimulationelectrodes 220. Controller 230 may also be used to control thestimulation levels and stimulation duration of spinal stimulationelectrodes 203, nerve stimulation electrodes 210 and cardiac stimulationelectrodes 220. Controller 230 may also gather and process informationfrom the various components of system 100. This information may be usedto adjust stimulation levels and stimulation times of spinal stimulationelectrodes 203, nerve stimulation electrodes 210 and cardiac stimulationelectrodes 220.

Unit 200 may incorporate one or more switches to facilitate regulationof the various components by the surgeon. One example of such a switchis shown as foot pedal 250. The switch may also be, for example, a handswitch, or a voice-activated switch comprising voice-recognitiontechnologies. The switch may be incorporated in or on one of thesurgeon's instruments, such as surgical site retractor, or any otherlocation easily and quickly accessed by the surgeon.

Unit 200 may also include a display 260. Unit 200 may also include othermeans of indicating the status of various components to the surgeon suchas a numerical display, gauges, a monitor display or audio feedback.Unit 200 may also include one or more visual and/or audible signals usedto prepare a surgeon for the start or stop of spinal cord stimulation,nerve stimulation and/or cardiac stimulation.

FIG. 3 shows a flow diagram of one embodiment of the present invention.The patient is prepared for a medical procedure at 500.

At this point, the spinal cord may be stimulated to alleviate thepatient's pain (Block 505). The spinal cord may also be stimulated tocontrol the patient's lungs or the functions of other organs. As seen inFIG. 3, spinal cord stimulation may occur throughout the entireprocedure in a continuous or intermittent manner.

At Block 510, a nerve that controls the beating of the heart isstimulated. Such a nerve may be for example a vagal nerve. At Block 510,one or more of a variety of pharmacological agents or drugs may bedelivered. These drugs may produce reversible asystole of a heart whilemaintaining the ability of the heart to be electrically paced.

A variety of pharmacological agents or drugs may also be delivered atother times during the procedure 500. These drugs may also producereversible asystole of a heart while maintaining the ability of theheart to be electrically paced. Other drugs may be administered for avariety of functions and purposes as described below. Drugs may bedelivered at any appropriate time during the medical procedure, forexample, at the beginning of the procedure, intermittently during theprocedure, continuously during the procedure or following the procedure.

Drugs, drug formulations or compositions suitable for administration toa patient during a medical procedure may include a pharmaceuticallyacceptable carrier or solution in an appropriate dosage. There are anumber of pharmaceutically acceptable carriers that may be used fordelivery of various drugs, for example, via direct injection, oraldelivery, suppository delivery, transdermal delivery, epicardialdelivery and/or inhalation delivery. Pharmaceutically acceptablecarriers include a number of solutions, preferably sterile, for example,water, saline, Ringer's solution and/or sugar solutions such as dextrosein water or saline. Other possible carriers that may be used includesodium citrate, citric acid, amino acids, lactate, mannitol, maltose,glycerol, sucrose, ammonium chloride, sodium chloride, potassiumchloride, calcium chloride, sodium lactate, and/or sodium bicarbonate.Carrier solutions may or may not be buffered.

Drug formulations or compositions may include antioxidants orpreservatives such as ascorbic acid. They may also be in apharmaceutically acceptable form for parenteral administration, forexample to the cardiovascular system, or directly to the heart, such asintracoronary infusion or injection. Drug formulations or compositionsmay comprise agents that provide a synergistic effect when administeredtogether. A synergistic effect between two or more drugs or agents mayreduce the amount that normally is required for therapeutic delivery ofan individual drug or agent. Two or more drugs may be administered, forexample, sequentially or simultaneously. Drugs may be administered viaone or more bolus injections and/or infusions or combinations thereof.The injections and/or infusions may be continuous or intermittent. Drugsmay be administered, for example, systemically or locally, for example,to the heart, to a coronary artery and/or vein, to a pulmonary arteryand/or vein, to the right atrium and/or ventricle, to the left atriumand/or ventricle, to the aorta, to the AV node, to the SA node, to anerve and/or to the coronary sinus. Drugs may be administered ordelivered via intravenous, intracoronary and/or intraventricularadministration in a suitable carrier. Examples of arteries that may beused to deliver drugs to the AV node include the AV node artery, theright coronary artery, the right descending coronary artery, the leftcoronary artery, the left anterior descending coronary artery andKugel's artery. Drugs may be delivered systemically, for example, viaoral, transdermal, intranasal, suppository or inhalation methods. Drugsalso may be delivered via a pill, a spray, a cream, an ointment or amedicament formulation.

Drugs may be delivered via a drug delivery device that may comprise acatheter, such as a drug delivery catheter or a guide catheter, a patch,such as a transepicardial patch that slowly releases drugs directly intothe myocardium, a cannula, a pump and/or a hypodermic needle and syringeassembly. A drug delivery catheter may include an expandable member,e.g., a low-pressure balloon, and a shaft having a distal portion,wherein the expandable member is disposed along the distal portion. Acatheter for drug delivery may comprise one or more lumens and may bedelivered endovascularly via insertion into a blood vessel, e.g., anartery such as a femoral, radial, subclavian or coronary artery. Thecatheter can be guided into a desired position using various guidancetechniques, e.g., flouroscopic guidance and/or a guiding catheter orguide wire techniques.

Drugs may be delivered via an iontophoretic drug delivery device placedon the heart. In general, the delivery of ionized drugs may be enhancedvia a small current applied across two electrodes. Positive ions may beintroduced into the tissues from the positive pole, or negative ionsfrom the negative pole. The use of iontophoresis may markedly facilitatethe transport of certain ionized drug molecules. For example, lidocainehydrochloride may be applied to the heart via a drug patch comprisingthe drug. A positive electrode could be placed over the patch andcurrent passed. The negative electrode would contact the heart or otherbody part at some desired distance point to complete the circuit. One ormore of the electrodes may also be used as nerve stimulation electrodes210 or as cardiac stimulation electrodes 220.

The two divisions of the autonomic nervous system that regulate theheart have opposite functions. First, the adrenergic or sympatheticnervous system increases heart rate by releasing epinephrine andnorepinephrine. Second, the parasympathetic system also known as thecholinergic nervous system or the vagal nervous system decreases heartrate by releasing acetylcholine. Catecholamines such as norepinephrine(also called noradrenaline) and epinephrine (also called adrenaline) areagonists for beta-adrenergic receptors. An agonist is a stimulantbiomolecule or agent that binds to a receptor.

Beta-adrenergic receptor blocking agents compete with beta-adrenergicreceptor stimulating agents for available beta-receptor sites. Whenaccess to beta-receptor sites are blocked by receptor blocking agents,also known as beta-adrenergic blockade, the chronotropic or heart rate,inotropic or contractility, and vasodilator responses to receptorstimulating agents are decreased proportionately. Therefore,beta-adrenergic receptor blocking agents are agents that are capable ofblocking beta-adrenergic receptor sites.

Since beta-adrenergic receptors are concerned with contractility andheart rate, stimulation of beta-adrenergic receptors, in general,increases heart rate, the contractility of the heart and the rate ofconduction of electrical impulses through the AV node and the conductionsystem.

Drugs, drug formulations and/or drug compositions that may be usedaccording to this invention may include any naturally occurring orchemically synthesized (synthetic analogues) beta-adrenergic receptorblocking agents. Beta-adrenergic receptor blocking agents orβ-adrenergic blocking agents are also known as beta-blockers orβ-blockers and as class II antiarrhythmics.

The term “beta-blocker” appearing herein may refer to one or more agentsthat antagonize the effects of beta-stimulating catecholamines byblocking the catecholamines from binding to the beta-receptors. Examplesof beta-blockers include, but are not limited to, acebutolol,alprenolol, atenolol, betantolol, betaxolol, bevantolol, bisoprolol,carterolol, celiprolol, chlorthalidone, esmolol, labetalol, metoprolol,nadolol, penbutolol, pindolol, propranolol, oxprenolol, sotalol,teratolo, timolol and combinations, mixtures and/or salts thereof.

The effects of administered beta-blockers may be reversed byadministration of beta-receptor agonists, e.g., dobutamine orisoproterenol.

The parasympathetic or cholinergic system participates in control ofheart rate via the sinoatrial (SA) node, where it reduces heart rate.Other cholinergic effects include inhibition of the AV node and aninhibitory effect on contractile force. The cholinergic system actsthrough the vagal nerve to release acetylcholine, which, in turn,stimulates cholinergic receptors. Cholinergic receptors are also knownas muscarinic receptors. Stimulation of the cholinergic receptorsdecreases the formation of cAMP. Stimulation of cholinergic receptorsgenerally has an opposite effect on heart rate compared to stimulationof beta-adrenergic receptors. For example, beta-adrenergic stimulationincreases heart rate, whereas cholinergic stimulation decreases it. Whenvagal tone is high and adrenergic tone is low, there is a marked slowingof the heart (sinus bradycardia). Acetylcholine effectively reduces theamplitude, rate of increase and duration of the SA node actionpotential. During vagal nerve stimulation, the SA node does not arrest.Rather, pacemaker function may shift to cells that fire at a slowerrate. In addition, acetylcholine may help open certain potassiumchannels thereby creating an outward flow of potassium ions andhyperpolarization. Acetylcholine also slows conduction through the AVnode.

Drugs, drug formulations and/or drug compositions that may be usedaccording to this invention may include any naturally occurring orchemically synthesized (synthetic analogues) cholinergic agent. The term“cholinergic agent” appearing herein may refer to one or morecholinergic receptor modulators or agonists. Examples of cholinergicagents include, but are not limited to, acetylcholine, carbachol(carbamyl choline chloride), bethanechol, methacholine, arecoline,norarecoline and combinations, mixtures and/or salts thereof.

Drugs, drug formulations and/or drug compositions that may be usedaccording to this invention may include any naturally occurring orchemically synthesized cholinesterase inhibitor. The term“cholinesterase inhibitor” appearing herein may refer to one or moreagents that prolong the action of acetylcholine by inhibiting itsdestruction or hydrolysis by cholinesterase. Cholinesterase inhibitorsare also known as acetylcholinesterase inhibitors. Examples ofcholinesterase inhibitors include, but are not limited to, edrophonium,neostigmine, neostigmine methylsulfate, pyridostigmine, tacrine andcombinations, mixtures and/or salts thereof.

There are ion-selective channels within certain cell membranes. Theseion selective channels include calcium channels, sodium channels and/orpotassium channels. Therefore, other drugs, drug formulations and/ordrug compositions that may be used according to this invention mayinclude any naturally occurring or chemically synthesized calciumchannel blocker. Calcium channel blockers inhibit the inward flux ofcalcium ions across cell membranes of arterial smooth muscle cells andmyocardial cells. Therefore, the term “calcium channel blocker”appearing herein may refer to one or more agents that inhibit or blockthe flow of calcium ions across a cell membrane. The calcium channel isgenerally concerned with the triggering of the contractile cycle.Calcium channel blockers are also known as calcium ion influxinhibitors, slow channel blockers, calcium ion antagonists, calciumchannel antagonist drugs and as class IV antiarrhythmics. A commonlyused calcium channel blocker is verapamil.

Administration of a calcium channel blocker, e.g., verapamil, generallyprolongs the effective refractory period within the AV node and slows AVconduction in a rate-related manner, since the electrical activitythrough the AV node depends significantly upon the influx of calciumions through the slow channel. A calcium channel blocker has the abilityto slow a patient's heart rate, as well as produce AV block. Examples ofcalcium channel blockers include, but are not limited to, amiloride,amlodipine, bepridil, diltiazem, felodipine, isradipine, mibefradil,nicardipine, nifedipine (dihydropyridines), nickel, nimodinpine,nisoldipine, nitric oxide (NO), norverapamil and verapamil andcombinations, mixtures and/or salts thereof. Verapamil and diltiazem arevery effective at inhibiting the AV node, whereas drugs of thenifedipine family have a lesser inhibitory effect on the AV node. Nitricoxide (NO) indirectly promotes calcium channel closure. NO may be usedto inhibit contraction. NO may also be used to inhibit sympatheticoutflow, lessen the release of norepinephrine, cause vasodilation,decrease heart rate and decrease contractility. In the SA node,cholinergic stimulation leads to formation of NO.

Other drugs, drug formulations and/or drug compositions that may be usedaccording to this invention may include any naturally occurring orchemically synthesized sodium channel blocker. Sodium channel blockersare also known as sodium channel inhibitors, sodium channel blockingagents, rapid channel blockers or rapid channel inhibitors.Antiarrhythmic agents that inhibit or block the sodium channel are knownas class I antiarrhythmics, examples include, but are not limited to,quinidine and quinidine-like agents, lidocaine and lidocaine-likeagents, tetrodotoxin, encainide, flecainide and combinations, mixturesand/or salts thereof. Therefore, the term “sodium channel blocker”appearing herein may refer to one or more agents that inhibit or blockthe flow of sodium ions across a cell membrane or remove the potentialdifference across a cell membrane. For example, the sodium channel mayalso be totally inhibited by increasing the extracellular potassiumlevels to depolarizing hyperkalemic values, which remove the potentialdifference across the cell membrane. The result is inhibition of cardiaccontraction with cardiac arrest (cardioplegia). The opening of thesodium channel (influx of sodium) is for swift conduction of theelectrical impulse throughout the heart.

Other drugs, drug formulations and/or drug compositions that may be usedaccording to this invention may include any naturally occurring orchemically synthesized potassium channel agent. The term “potassiumchannel agent” appearing herein may refer to one or more agents thatimpact the flow of potassium ions across the cell membrane. There aretwo major types of potassium channels. The first type of channel isvoltage-gated and the second type is ligand-gated.Acetylcholine-activated potassium channels, which are ligand-gatedchannels, open in response to vagal stimulation and the release ofacetylcholine. Opening of the potassium channel causeshyperpolarization, which decreases the rate at which the activationthreshold is reached. Adenosine is one example of a potassium channelopener. Adenosine slows conduction through the AV node. Adenosine, abreakdown product of adenosine triphosphate, inhibits the AV node andatria. In atrial tissue, adenosine causes the shortening of the actionpotential duration and causes hyperpolarization. In the AV node,adenosine has similar effects and also decreases the action potentialamplitude and the rate of increase of the action potential. Adenosine isalso a direct vasodilator by its actions on the adenosine receptor onvascular smooth muscle cells. In addition, adenosine acts as a negativeneuromodulator, thereby inhibiting release of norepinephrine. Class IIIantiarrhythmic-agents also known as potassium channel inhibitorslengthen the action potential duration and refractoriness by blockingthe outward potassium channel to prolong the action potential.Amiodarone and d-sotalol are both examples of class III antiarrhythmicagents.

Potassium is the most common component in cardioplegic solutions. Highextracellular potassium levels reduce the membrane resting potential.Opening of the sodium channel, which normally allows rapid sodium influxduring the upstroke of the action potential, is therefore inactivatedbecause of a reduction in the membrane resting potential. The presentinvention may be combined with conventional CPB; the induced asystole asdescribed by this invention may serve as a substitute for conventionalcardioplegic arrest. For example, the combination of drugs and vagalstimulation may be used as a cardioplegic agent in a variety of medicalprocedures.

Drugs, drug formulations and/or drug compositions that may be usedduring according to this invention may comprise one or more of anynaturally occurring or chemically synthesized beta-blocker, cholinergicagent, cholinesterase inhibitor, calcium channel blocker, sodium channelblocker, potassium channel agent, adenosine, adenosine receptor agonist,adenosine deaminase inhibitor, dipyridamole, monoamine oxidaseinhibitor, digoxin, digitalis, lignocaine, bradykinin agents,serotoninergic agonist, antiarrythmic agents, cardiac glycosides, localanesthetics and combinations or mixtures thereof. Digitalis and digoxinboth inhibit the sodium pump. Digitalis is a natural inotrope derivedfrom plant material, while digoxin is a synthesized inotrope.Dipyridamole inhibits adenosine deaminase, which breaks down adenosine.Drugs, drug formulations and/or drug compositions capable of reversiblysuppressing autonomous electrical conduction at the SA and/or AV node,while still allowing the heart to be electrically paced to maintaincardiac output may be used according to this invention.

In one embodiment, the cardiac asystole produced in accordance with thepresent invention is reversible, e.g., chemically such as by theadministration of atropine or by natural forces. Beta-adrenergicstimulation or administration of calcium solutions may be used toreverse the effects of a calcium channel blocker such as verapamil.Agents that promote heart rate and/or contraction may be used in apreferred embodiment of the present invention. For example, dopamine, anatural catecholamine, is known to increase contractility. Positiveinotropes are agents that specifically increase the force of contractionof the heart. Glucagon, a naturally occurring hormone, is known toincrease heart rate and contractility. Glucagon may be used to reversethe effects of a beta-blocker since its effects bypass thebeta-receptor. Forskolin is known to increase heart rate andcontractility. As mentioned earlier, epinephrine and norepinephrinenaturally increase heart rate and contractility. Thyroid hormone,phosphodiesterase inhibitors and prostacyclin, a prostaglandin, are alsoknown to increase heart rate and contractility. In addition,methylxanthines are known to prevent adenosine from interacting with itscell receptors.

At Block 520, a medical procedure may be performed or begun. Such aprocedure may be for example surgery on the heart. Alternatively, theprocedure may be surgery performed on another organ of the body.Alternatively, the procedure may be a procedure such as delivery of ababy.

The term “medical procedure” may mean any one or more medical orsurgical procedures such as, for example cardiac surgery, performed withor without cardiopulmonary bypass (CPB) circuits, heart valve repair,heart valve replacement, MAZE procedures, revascularization procedures,transmyocardial revascularization (TMR), percutaneous myocardialrevascularization (PMR) procedures, CABG procedures, anastomosisprocedures, non-surgical procedures, fluoroscopic procedures, beatingheart surgery, vascular surgery, neurosurgery, brain surgery,electrophysiology procedures, diagnostic and therapeutic procedures,ablation procedures, ablation of arrhythmias, endovascular procedures,treatment of the liver, spleen, heart, lungs, and major blood vessels,aneurysm repair, imaging procedures of the heart and great vessels, CATscans or MRI procedures, pharmacological therapies, drug deliveryprocedures, gene therapies, cellular therapies, cancer therapies,radiation therapies, genetic, cellular, tissue and/or organ manipulationor transplantation procedures, coronary angioplasty procedures,placement or delivery of coated or noncoated stents, atherectomyprocedures, atherosclerotic plaque manipulation and/or removalprocedures, birthing procedures, procedures where bleeding needs to beprecisely controlled, procedures that require precise control of cardiacmotion and/or bleeding.

When the medical procedure comprises one or more medical devices, e.g.,coated stents, these devices may be coated with one or more radioactivematerials and/or biological agents such as, for example, ananticoagulant agent, an antithrombotic agent, a clotting agent, aplatelet agent, an anti-inflammatory agent, an antibody, an antigen, animmunoglobulin, a defense agent, an enzyme, a hormone, a growth factor,a neurotransmitter, a cytokine, a blood agent, a regulatory agent, atransport agent, a fibrous agent, a protein, a peptide, a proteoglycan,a toxin, an antibiotic agent, an antibacterial agent, an antimicrobialagent, a bacterial agent or component, hyaluronic acid, apolysaccharide, a carbohydrate, a fatty acid, a catalyst, a drug, avitamin, a DNA segment, a RNA segment, a nucleic acid, a lectin, anantiviral agent, a viral agent or component, a genetic agent, a ligandand a dye (which acts as a biological ligand). Biological agents may befound in nature (naturally occurring) or may be chemically synthesized.

The medical procedure may be non-invasive, minimally invasive and/orinvasive. The medical procedure may entail a port-access approach, apartially or totally endoscopic approach, a sternotomy approach or athoracotomy approach. The medical procedure may include the use ofvarious mechanical stabilization devices or techniques as well asvarious robotic or imaging systems.

In one method, the heart may be temporarily slowed or intermittentlystopped for short periods of time to permit the surgeon to accomplishthe required surgical task and yet still allow the heart itself tosupply blood circulation to the body. For example, stimulation of thevagus nerve in order to temporarily and intermittently slow or stop theheart is described in U.S. Pat. No. 6,006,134 entitled “Method andDevice for Electronically Controlling the Beating of a Heart UsingVenous Electrical Stimulation of Nerve Fibers”, Dec. 21, 1999, toinventors Hill and Jonkman. This patent is assigned to Medtronic, Inc.and is incorporated herein by reference.

After a time, the medical procedure or one phase of the procedure iscompleted at 520. After some phase of the medical procedure isperformed, cardiac contractions are allowed to occur (Block 530).Cardiac contractions may need to occur intermittently during theprocedure to ensure adequate blood flow. In one embodiment, thestimulation from the nerve stimulator 10 is stopped or slowed enough toallow the heart to contract. For example, the vagal nerve stimulation isremoved, thereby allowing cardiac contractions to occur.

In another embodiment, the heart may be stimulated to ensure thatcardiac contractions occur (Block 535). For example, cardiac stimulator20 may be used to apply pacing pulses to the heart to encourage theheart to contract normally. In particular, the pacing pulses may beapplied to the ventricle as is well known in the field.

The present invention permits the heart to be stilled for selected andcontrollable periods of time in order to permit a medical procedure,such as cardiac surgery or other surgery, to be performed. While such aperiod of stillness is desired, it must not last too long, otherwiseinsufficient blood and oxygen is delivered to organs. Thus, it isnecessary to have the periods when the heart is beating (Blocks 530,535).

If additional medical procedures or additional stages of medicalprocedures need to be performed, the heart may again be stilled usingthe methods of stilling the heart described above. Therefore from Block530 or Block 535, the method may be repeated (loop designated by Block540). For example, the heart may again be prevented from contracting bystimulation of the vagal nerve (Block 510). Additional drugs may bedelivered or the drugs previously administered may continue to beadministered.

Additional steps of the medical procedure or additional medicalprocedures may be performed (Block 520) while the heart is still. Then,this stage of stillness may be followed by another stage when thestimulation is removed (Block 530) and the heart is allowed to contract.Again, the heart may be stimulated to encourage contractions (Block535).

This cycle may be repeated until the procedure, such as the surgery, iscompleted. After the procedure is completed, step 535 may be performeduntil the heart is beating normally. In addition, one or more of avariety of pharmacological agents or drugs may be delivered or maycontinue to be delivered after the procedure is completed.

For example, a surgical procedure at 520 may require several stitches tobe made by the surgeon. The surgeon may stimulate the vagal nerve at 510to stop the heart. Then the surgeon may make the first stitch at 520.The surgeon may then reduce or halt stimulation at 530 and allow theheart to contract. The surgeon may also pace the heart at 535. Then at540, the surgeon may return to 510 to inhibit contractions of the heart.At 520, the surgeon will then make the second stitch. This process maybe repeated (the loop designated by 540 may be repeated) until all therequired stitches have been made.

In one embodiment, after the surgery is completed, step 535 is performeduntil the heart is beating normally. Finally, after the patient's painshould be sufficiently tolerable, the spinal stimulation may beterminated (Block 545). Alternatively, the spinal cord stimulator may bepermanently or semi-permanently implanted in the patient.

FIG. 4 is a timeline illustrating one embodiment of the relationshipbetween spinal cord stimulation, vagal nerve stimulation and cardiacstimulation.

Point 610 indicates a point before the medical procedure has begun. Atthis point 610, both nerve stimulation and cardiac stimulation are off.At point 610, the heart is beating regularly. Stimulation to the spinalcord may be off at point 610 or may be begun at this point.

Then nerve stimulation is turned on to inhibit beating of the heart.During phase 601, the vagal nerve stimulation is on and the cardiacstimulation is off. This is the condition of the two types ofstimulation at step 520 described above. In one embodiment, shown inFIG. 3 spinal cord stimulator 3 is on throughout the entire procedure.Alternatively, spinal cord stimulation may be turned on intermittentlyduring the procedure.

Point 611 is a representative point during phase 601. At point 611, thecontractions of the heart are stilled or substantially slowed. Spinalcord stimulation may still occur at point 611.

During phase 602 the vagal stimulation is turned off (as described atstep 530) and the cardiac stimulation may be turned on (as described at535). Point 612 is a representative point during phase 602. At point612, the contractions are allowed and/or may be induced. In oneembodiment, spinal cord stimulation is on during phase 602.

During phase 603, the vagal nerve stimulation is again turned on and thecardiac stimulation is turned off. During phase 604 the vagalstimulation is again turned off and the cardiac stimulation may again beturned on.

The method of the present invention may be repeated as necessary until apoint is reached, represented by point 615, when the necessary medicalprocedures are completed. At this point 615, nerve stimulation is offalthough cardiac stimulation may be left on in order to pace the heartto its normal rhythm. At point 615, spinal cord stimulation may beturned off as described at Block 545. Alternatively, spinal cordstimulation may continue as needed.

It will be appreciated by those skilled in the art that while theinvention has been described above in connection with particularembodiments and examples, the invention is not necessarily so limited,and that numerous other embodiments, examples, uses, modifications anddepartures from the embodiments, examples and uses are intended to beencompassed by the claims attached hereto. The entire disclosure of eachpatent and publication cited herein is incorporated by reference, as ifeach such patent or publication were individually incorporated byreference herein.

We claim:
 1. A system for performing a medical procedure, comprising: a spinal stimulator to reduce pain during the medical procedure; a nerve stimulator in communication with the spinal stimulator to inhibit beating of the heart; and a cardiac stimulator in communication with the spinal stimulator to stimulate beating of the heart.
 2. The system of claim 1 further comprising: drug delivery means for delivering at least one drug during the medical procedure.
 3. The system of claim 1 wherein the drug delivery means are selected from the group consisting of: a spray, a cream, an ointment, a medicament, a pill, a patch, a catheter, a cannula, a needle and syringe, a pump, and an iontophoretic drug delivery device.
 4. The system of claim 1 wherein the nerve stimulator stimulates a parasympathetic nerve fiber.
 5. The system of claim 1 wherein the nerve stimulator stimulates a nerve selected from the group consisting of: a vagal nerve, a carotid sinus nerve, a fat pad.
 6. The system of claim 1 wherein the spinal stimulator comprises at least one electrode.
 7. The system of claim 6 wherein the electrode is selected from the group consisting of: spinal stimulation electrodes, balloon-type electrodes, basket-type electrodes, umbrella-type electrodes, suction-type electrodes, guided catheters, guided electrodes, steerable catheters, and steerable electrodes.
 8. The system of claim 1 wherein the nerve stimulator comprises at least one electrode.
 9. The system of claim 8 wherein the electrode is selected from the group consisting of: nerve stimulation electrodes, endotracheal electrodes, endoesophageal electrodes, intravascular electrodes, transcutaneous electrodes, intracutaneous electrodes, balloon-type electrodes, basket-type electrodes, umbrella-type electrodes, tape-type electrodes, suction-type electrodes, screw-type electrodes, barb-type electrodes, bipolar electrodes, monopolar electrodes, metal electrodes, wire electrodes, patch electrodes, cuff electrodes, clip electrodes, needle electrodes and probe electrodes.
 10. The system of claim 1 wherein the cardiac stimulator comprises at least one electrode.
 11. The system of claim 9 wherein the electrode is selected from the group consisting of: cardiac stimulation electrodes, clip electrodes, needle electrodes, probe electrodes, pacing electrodes, epicardial electrodes, patch electrodes, intravascular electrodes, balloon-type electrodes, basket-type electrodes, tape-type electrodes, umbrella-type electrodes, suction-type electrodes, endotracheal electrodes, endoesophageal electrodes, transcutaneous electrodes, intracutaneous electrodes, screw-type electrodes, barb-type electrodes, bipolar electrodes, monopolar electrodes, metal electrodes, wire electrodes and cuff electrodes.
 12. The system of claim 1 further comprising: a processor operatively connected to the spinal stimulator, the nerve stimulator and the cardiac stimulator.
 13. The system of claim 12 wherein the processor processes output from the spinal stimulator and adjusts output from the nerve stimulator based on output from the spinal stimulator.
 14. The system of claim 12 wherein the processor processes output from the spinal stimulator and adjusts output from the cardiac stimulator based on output from the spinal stimulator. 